The present invention relates to mechanical devices and methods for recycling contaminated liquids.
Demand for recycling of contaminated industrial liquids has increased dramatically in recent years as a result of growing concern over the deleterious environmental impact of unregulated disposal of such liquids. The current costs of proper disposal of certain industrial liquids, such as metalworking coolants and lubricants, frequently exceed their purchase costs. Consequently, maximizing the useful life of such liquids, through recycling, offers significant economic and environmental benefits.
Metalworking coolants and lubricants are but a typical example of a vast array of industrial liquids that pose potential environmental hazards and are amenable to recycling. Other examples include hydraulic fluid for operating hydraulic motors and vehicle lifts, used motor oil, antifreeze and many petroleum-based liquids contaminated with water-based liquids, and vice versa.
Some progress has been made in providing recycling devices for specific needs. Large users of certain liquids have installed on-site recycling systems that utilize fine screens to separate particulate contaminants, and centrifuges to separate components of immiscible liquids. Large manufacturers may employ a recycling processing system that moves within a plant to different metalworking machines to filter the machine tool coolant, as shown in U.S. Pat. No. 4,772,402 to Love. Smaller manufacturers could utilize a trailer or truck borne device, on a periodic basis, that screens, pasteurizes and then centrifuges metalworking coolants, as shown in U.S. Pat. No. 4,636,317 to Lewis.
Unfortunately, none of these alternatives have gained widespread acceptance. The principal impediments to the commercial viability of such recycling devices are, first, the extraordinary variety of environmentally hazardous industrial liquids and, second, the diverse nature of the users of such liquids. From General Motors Corporation to corner automobile service stations and small metalworking "job shops", industrial coolants, lubricants and related liquids are employed in huge quantities under varying conditions.
Some liquids are employed at a specific temperature range that encourages rapid bacterial growth, producing corrosive metabolites and related by-products. Another user may employ the exact same liquid at a different temperature such that the resulting contamination problem is primarily from particulate matter or possibly contamination with an insoluble liquid. A particular user may exhaust a substantial quantity of a first specific liquid while only a smaller quantity of a second hazardous liquid is depleted during the same period of time. Acquisition of an on-site recycling system may not include recycling of both liquids due to the differing characteristics of the liquids. Known mobile recycling devices may not economically recycle both liquids. Therefore, such a user could tend to invest in premature, off-site disposal only, because some off-site disposal would always be necessary.
Additionally, most contaminated industrial liquids are stored in a manner that complicates recycling. Storage containers of the liquids typically produce stratified layers. A top layer may consist of foam with fine particulate matter ("fines") adhering to bubbles. An intermediate layer below the foam may include the lighter of two insoluble liquids, such as a petroleum-based liquid. The bulk of the liquid may be another lower layer of a heavier insoluble liquid, with a final bottom layer of settled fines and precipitated by-products of microbial activity.
Known systems for recycling such contaminated liquids are designed to operate on liquids having specific characteristics. The systems cannot be readily altered to adapt to different liquids or the stratified layers found in specific, contaminated, stored liquids. The systems are designed to set an intake side of the recycling system to a specific flow-rate appropriate to produce specific temperature ranges and centrifugation effects. Once the intake flow-rate is set, the systems operate on a straight-run mode affording no mid-run testing and change to satisfy requirements of changing characteristics of the liquid as a storage container is depleted, or when the intake moves from one storage container (e.g., a fifty-five gallon barrel) to another.
Another reason known recycling systems have not attained wide-spread commercial success is that certain industrial liquids contain a variety of chemical additives in relatively small quantities. These additives are very important in determining the effectiveness of the liquids. They include biocides (bacterial growth suppressing agents), pH buffers, emulsifying agents, anti-foam chemicals, deodorizers, concentrated liquid boosters, among others. The depletion or deterioration of such agents varies with the nature of use and conditions of storage of the liquids. Current recycling systems are unable to monitor the additive requirements of filtered liquids during recycling. Post recycling testing to determine additive requirements is a lengthy, costly and ineffective procedure.
Still another problem with existing recycling systems is the substantial energy requirement to economically operate the systems. The energy required to heat typical contaminated liquids to an effective pasteurizing temperature, at a flow-rate that is commercially viable, requires known mobile trailer or truck borne systems to utilize electrical energy provided at the storage site of the contaminated liquid. Although this is possible at some large facilities, such a requirement presents significant logistical problems in most circumstances. Additionally, the billing complications arising from such an energy-use arrangement deters periodic utilization of a mobile recycling system-contractor.
Consequently, because of structural limitations, known liquid recycling systems are unable to effectively recycle the wide variety of hazardous industrial liquids or service the periodic recycling needs of most hazardous liquid users.
Accordingly, it is the general object of the present invention to provide an improved liquid recycling system that overcomes the problems of the prior art.
It is another general object to provide an improved liquid recycling system that offers an inexpensive alternative to costly premature disposal of hazardous industrial liquids.
It is a more specific object to provide a liquid recycling system that can readily change its filtering capacities to efficiently service a variety of different hazardous industrial liquids.
It is another object to provide a liquid recycling system that can readily change its filtering capacities, while recycling a hazardous industrial liquid.
It is another object to provide a liquid recycling system that affords monitoring of chemical additive requirements of the liquid being recycled, and provides for metering of such additives into the liquid, during recycling.
It is yet another object to provide a liquid recycling system that is mobile and self-powered.
The above and other objects and advantages of this invention will become more readily apparent when the following description is read in conjunction with the accompanying drawings.